The Focus is Ford's entry-level car available in a number of body styles, from a hatchback to a four-door sedan. It provides easy access for do-it-yourself mechanics. Look for a white, chalky substance on the battery as a sign it needs replacing.
Locate the battery on the driver's side close to the inside wall. Remove the bar that holds in the battery with a screwdriver.
Disconnect the ground wire. Set it aside so that it doesn't touch anything metal. Remove the cable ends from the battery terminals with a battery terminal puller. Take off the negative terminal first.
Lift the battery out of the compartment. Use the wire brush to clean the surface that holds the battery. Clean the insides of the connector cables with a pointed wire brush.
Rinse off the cables and battery tray or wipe with a damp cloth, and let them dry out.
Place the new battery on the shelf. Place the correct cable on each terminal and tighten securely with pliers or a socket wrench. Replace the battery holder.
Dispose of the old battery properly at an auto parts store or recycling center.
Never smoke when replacing a battery. Wear goggles and gloves when handling the battery and battery cables in case of contact with acid.